well i first tried the wd40. it has one major drawback, it is too runny. just wants to drip/run off. looked like it was working though.
simple green did NOT touch the tar. not even a little bit.
so, at wallyworld i bought some "Tar & Bug" remover made by Gunk. it was the cheapest one on the shelf i think. somewhat thicker than wd40, but not as thick as i would like (oh, say 90wt would be nice). it semi looks like and smells like diesel and something else blended. it got it all off without a problem and the can says "clear coat safe".
then i washed and waxed the whole truck.
sorry, no pics. i forgot.